Standard F 1236 is a guide for the visual

inspection of gloves, sleeves, and other such rubber insulating equipment. Rubber gloves are available in six basic voltage classes from class 00 to class 4, and two different types: types I and II. Table 2.8 identifies each class, its maxi- mum use voltage, and the root-mean- square (rms) and direct current (dc) voltages that are used to proof-test the gloves. Figure 2.14 shows the general design and dimensions of rubber gloves. Rubber gloves are available in the follow- ing lengths:

2.18 CHAPTER TWO

Table 2.9 lists minimum and maximum thicknesses for the six classes of gloves. In addition to the voltage classes, rubber gloves are available in two different types: type I which is not ozone-resistant and type II which is ozone-resistant.

All rubber goods must have an attached, color-coded label subject to the minimum requirements specified in Table 2.10.

When to Use Rubber Gloves. Rubber gloves and their leather protectors should be worn any time there is danger of injury due to contact between the hands and energized parts of the power system. Each of the work situations described in Table 2.7 should require the use of rubber gloves and their leather protectors.

Rubber gloves should also be worn anytime a worker’s hands are closer to an energized conductor than the distance specified by the restricted approach boundary. See Chap. 3 for the definition and calculation methods for the restricted approach boundary.

FIGURE 2.14 Dimension measurements for standard and contour cuff rubber gloves. (Courtesy ASTM.)

When to Use Leather Protectors. As stated earlier in this chapter, leather protectors should always be used over rubber gloves to provide mechanical protection for the insulat- ing rubber. Furthermore, leather protectors should never be used for any purpose other than protecting rubber gloves.

Sometimes the need for additional dexterity may require that the leather protectors not be used. The various industry standards allow such an application in only three situations.

● Class 00 Up to and including 250 V, leather protectors may be omitted for Class 00 gloves. Such omission is only permitted under limited-use conditions when small-parts manipulation requires unusually good finger dexterity.

● _{Class 0 Leather protectors may be omitted under limited-use conditions when small-}

parts manipulation requires unusually good finger dexterity.

● Classes 1, 2, 3, 4 Under limited use conditions the leathers may be omitted. However: When the leathers are omitted for these classes, the user must employ gloves rated at least one (1) voltage class higher than normal. For example, if working in a 4160-Volt circuit without leather protectors, the worker must use Class 2 gloves.

Leather protectors should never be omitted if there is even a slight possibility of physi- cal damage or puncture. Also, rubber gloves previously used without protectors shall not be used with protectors until given an inspection and electrical retest.

How to Use Rubber Gloves. Rubber gloves should be thoroughly inspected and air-tested before each use. They may be lightly dusted inside with talcum powder or manufacturer- supplied powder. This dusting helps to absorb perspiration and eases putting them on and removing them. Caution: Do not use baby powder on rubber gloves. Some baby powder

ELECTRICAL SAFETY EQUIPMENT 2.19

Minimum thickness

Class of In crotch Other than crotch Maximum thickness

glove mm in mm in mm in 00 0.20 0.008 0.25 0.010 0.75 0.030 0 0.46 0.018 0.51 0.020 1.02 0.040 1 0.63 0.025 0.76 0.030 1.52 0.060 2 1.02 0.040 1.27 0.050 2.29 0.090 3 1.52 0.060 1.90 0.075 2.92 0.115 4 2.03 0.080 2.54 0.100 3.56 0.140

Source: Courtesy ASTM.

TABLE 2.9 Rubber Glove Thickness Standard

• Color coding according to voltage class: class 00–beige. class 0–red, class 1–white, class 2–yellow, class 3–green, class 4–orange.

• Manufacturer’s name • Voltage class (00, 0, 1, 2, 3, 4) • Type

• Size (gloves only)

2.20 CHAPTER TWO

products contain additives which can damage the glove and reduce its life and effectiveness. Cotton inserts are highly recommended for worker confort and convenience.

Rubber gloves should be applied before any activity that exposes the worker to the pos- sibility of contact with an energized conductor. As previously stated, anytime the worker’s hands must be closer to an energized conductor than the restricted approach boundary, rub- ber gloves must be worn. Be certain to wear the leather protector with the glove. Always check the last test date marked on the glove and do not use it if the last test was more than 6 months earlier than the present date.

Rubber Mats

Description. Rubber mats are used to cover and insulate floors for personnel protection. Rubber insulating mats should not be confused with the rubber matting used to help pre- vent slips and falls. This type of mat is sold by many commercial retail outlets and is not intended for electrical insulation purposes. Rubber insulating mats will be clearly marked and labeled as such.

Insulating rubber matting has a smooth, corrugated, or diamond design on one surface and may be backed with fabric. The back of the matting may be finished with cloth imprint or other slip-resistant material.

Construction and Standards. The ASTM standard D-178 specifies the design, construc- tion, and testing requirements for rubber matting.

Rubber mats are available in five basic voltage classes, from class 0 to class 4, in two different types, and in three different subcategories. Table 2.8 identifies each class, its max- imum use voltage, and ac rms and dc voltages that are used to test them. Table 2.11 identi- fies each of the types and special properties for insulating mats. Table 2.12 identifies the thickness requirements for insulating mats. Table 2.13 identifies the standard widths for insulating rubber matting.

Rubber mats must be clearly and permanently marked with the name of the manufac- turer, type, and class. ASTM D-178 must also appear on the mat. This marking is to be placed a minimum of every 3 ft (1 m).

When to Use Rubber Mats. Employers should use rubber mats in areas where there is an ongoing possibility of electric shock. Because permanently installed rubber mats are sub- ject to damage, contamination, and embedding of foreign materials, they should not be relied upon as the sole or primary source of electrical insulation.

Type I Type II

Composition Made of any elastomer or combi- Made of any elastomer or nation of elastomeric compounds, combination of elastomeric

properly vulcanized compounds with one or more of

the special properties listed by subcategory

Subcategories None A: Ozone resistant

B: Flame resistant C: Oil resistant

How to Use Rubber Mats. Rubber mats are usually put in place on a permanent basis to provide both electrical insulation and slip protection. Mats should be carefully inspected before work is performed which may require their protection. Rubber mats should only be used as a backup type of protection. Rubber blankets, gloves, sleeves, and other such per- sonal apparel should always be employed when electrical contact is likely.

Rubber Blankets

Description. Rubber blankets in Fig. 2.15 are rubber insulating devices that are used to cover conductive surfaces, energized or otherwise. They come in a variety of sizes and are used any- time employees are working in areas where they may be exposed to energized conductors.

Construction and Standards. The ASTM publishes three standards which affect the con- struction and use of rubber blankets.

1. Standard D 1048 specifies manufacturing and technical requirements for rubber blankets.